When planting or drilling where residue covers the intended seed bed, it is necessary to cut through such residue and initiate a tilled slice in the soil that is then entered and reshaped by the trailing opener, such as the double disk type, for deposit of seeds. It is important, however, that the initial slit made by the coulter or other device ahead of the opener be of consistent depth so that the seed which is deposited several feet behind the coulter is likewise deposited at the desired depth. If the coulter cuts too deeply, the seed when deposited by the opener may ultimately be buried more deeply than desired so as to delay emergence, or perhaps an air pocket could develop beneath the seed since the opener has its own gaging mechanism to cause it to deposit the seed at a selected depth.
On the other hand, if the slit made by the coulter is too shallow, the double disks of the opener may be unable to cut through the soil sufficiently to deepen the slit; consequently, the seed will lie closer to the surface than desired and may not be adequately protected against adverse weather elements. The problem of accurate seed placement is particularly compounded in such low tillage or no tillage situations because the soil itself has not been loosened and fluffed ahead of time in preparation for the movement therethrough of the opening disks or other seed placement structure.
In typical seed planting or drilling equipment, the ground wheels that support the frame which carries the slicing coulters are located a substantial distance behind the coulters themselves. Consequently, rises or falls in the terrain are encountered first by the coulters, and only later by the ground wheels. Consequently, the ground wheels are not responsive soon enough to terrain changes to adjust the height of the frame. By the time the terrain change is experienced by the ground wheels, it may be too late to raise or lower the coulters; in fact, changing the coulter depth at that point may actually move the coulters in the wrong direction.
What is needed is a means of making the frame responsive to changes encountered by the coulters themselves at the time such changes are encountered, rather than relying upon the trailing support wheels to do that job.